Proposing: Accelerating spaceprobes via centrifuge and material stability until such speeds as to bend then fold spacetime near then beyond lightspeed.
Swing the spaceprobe around and around, cooling the ropes via laser cooling while holding and reinforcing integrity, until spacetime starts to bend. Add more rope length as necessary to keep the probe in position while spacetime stretches and a different geometry is necessary. Then, when accelerated enough the soft and slow way, sharp inverting and pulling the ropes while twisting and coiling them too, less worrying about keeping structure and more worrying about doing it fast, so spacetime folding occurs via the weight and destruction of the ropes themselves.
Complex concept: inner swinger, and outer ring swinger, and a train overspeeding on the ring, and many ropes and pulleys on the train, spread around to distribute and accentuate the spacetime bending forces needed, from rough prolonged power to sharp expression of it, to accelerate just a little bit of matter to relativistic speeds. Even if we trick nature into taking the energy by swinging the spaceprobe for a long while, it will still be a lot of ropes needed to hold a lot (but less) of ropes that are hanging at forces comparable to the event horizon of a black hole.
When the launch moment arrives, the ropes that bent spacetime are pulled fast out of the way, while the probe is given a final nudge via conventional push methods - impact, electric fields, lasers and rockets. For the sharp reverse it is necessary that inertial rings and trains are already spinning, and reversing is as fast as switching hook, not inverting motors.
Maybe tricking spacetime with outer ring to pull the probe is not enough? The whole structure can be pulled in a similar way by an even bigger structure, with or without great rings since this kind of recursion amplifies nicely by itself for most of the bending of spacetime (until the very moment where spacetime needs to fold beyond lightspeed limit, in which case the catapult needs all the material help it can get from anywhere it can get it, thus, outer ring is an emergent necessity because catapult recursion may not be enough).
For a size/speed comparison, lightspeed does 7.5 orbits at the surface of Earth per second, or 75 orbits at 1/10 of that distance, or 750 cycles at 1/100, or 7500 cycles per second at 1/1000 of that distance (recursive catapult level). At the LHC, protons near lightspeed go at just over 11000 cycles per second (outer ring level). So, as space structure, this is good to go in my opinion. For example, the outer ring rotating with perimeter speed 1% of destination speed, and train on it, and motor and pulleys on ropes, make it appear to the probe as pulling at 10x that, 10% of the destination speed. Then, at launch, the trick of inverting hook into another running massive inertial ring, makes it appear briefly to the probe as the destination speed, and so unlock, and shoot forth, and safe travels. With an outer ring the size of the LHC rotating on the buildup of speed till 100 cycles a second, lightspeed bending is within reach without overly complicating the catapult. The central pull is much more adapt to higher speeds, and maybe can even reach the desired speeds by itself, but it is expected that conventional materials would fail to accelerate anything big, even with recursive catapult, without support from a bigger ready structure spinning independently. The difference may be as if between sending a camera that takes photos to send home, or a human habitat.
For the outer ring it may be necessary to prepare ropes ahead, already curbed in the position they would take, or some less complex but still necessary trick, pulling the ropes without pulling the probe.
Once reaching spacetime bending near lightspeed equivalent, speculation is that crossing over is alike to entering a black hole. This may be like crossing over regular space, the old cosmos is far away and the destination is local (most likely), or, it may need to break through forcefully (similar to breaking the sound barrier).
Should force be needed to cross this apparent event horizon, there may be many solutions, for example spearing through, or more complex geometries based on spear and including space for what comes out of the event horizon in reflection to what goes in. I have an idea about one such complex geometry that can pass through the event horizon of a black hole, and the action necessary immediately during, that I will publish in a future blog.
Our civilization needs to learn to exist with 'the other', which includes our own extended and unretractable reach. This idea, as here presented, has occurred to aliens throughout the cosmos already, if they exist. And it does not need to do 200% or 99% lightspeed to make you blink, because it is faster than all current tech at 1% too. Sprinkle in here some Oumuamua possibilities, and you got the recipe for a very tasty explorable cosmos within reach.
Cosmic aliens we may meet, or we may become, but fractaliens we will meet and become after the #FractalUniverseRevolution expands our each beyond physics itself!